The present invention is directed to a hydrogen getter material comprising a mixture of a polyphenyl ether and a hydrogenation catalyst, preferably a metal selected from Group VIII of the Periodic Table of the Elements.
In many applications the presence of hydrogen and its isotopes, arising from various chemical and electrochemical corrosion reactions, can be detrimental. Hydrogen can evolve from corrosion by atmospheric gases by stray electric currents, from electronic devices, which can include batteries operating in normal or abnormal condition, and from leaky hydrogen piping. The accumulation of hydrogen can present a significant fire and/or explosion hazard particularly in sealed components where special precautions may need to be taken to prevent dangerously high internal pressures from developing. Hydrogen corrosion is a particular problem in downhole fiber optic systems. Hydrogen attack in fiber optic systems reduces the optical transmission efficiency of these devices.
It has long been known that hydrogen absorbing materials, known as getters, can be used to counteract hydrogen accumulation. Ayers et al. discuss the use of active metals such as zirconium or titanium, and alloys thereof in U.S. Pat. No. 4,512,721. These metals are capable of maintaining low hydrogen partial pressures but have the disadvantage of requiring high temperatures for initial activation and/or ongoing operation (generally greater than 300° C.) because of the necessity to diffuse surface contaminants into the bulk metal, thereby providing a fresh surface for continued hydrogen absorption.
Labaton, in U.S. Pat. No. 4,886,048, describes another means for removing hydrogen by reacting the hydrogen with oxygen to form water in the presence of a noble metal catalyst such as palladium, and trapping the water on a water absorbing material such as a molecular sieve. However, hydrogen getters of this type are expensive, bulky, limited by the availability of oxygen, and capable of causing a detonation if improperly formulated.
Conventional hydrogen getters, such as those described in the above-referenced patens are expensive, can require special operating conditions such as high temperature regimes or ancillary reactants in order to maintain low hydrogen partial pressures. These generally will not work well in the presence of water or they may not work at all; they may require the presence of oxygen, be poisoned by oxygen, and may pose significant safety hazards, including fire and explosion if handled improperly, for example, by exposure to air.
In order to overcome the aforementioned problems with conventional hydrogen getters, Shepodd in U.S. Pat. Nos. 5,703,378, 5,837,158 and 5,624,598 discloses and describes organic getter systems that employ unsaturated organic compounds combined (i.e., organic compounds that contain carbon-carbon double or triple bonds) with noble metal catalysts as hydrogen getter materials. While these organic getter systems have been shown to work well for temperatures below about 200° C., because of the presence of double or triple bonds in these prior art hydrogen getters they begin to degrade appreciably at temperatures above 200° C. and slowly over time at temperatures above about 150° C. Moreover, the unsaturated organic compounds will polymerize at elevated temperatures, thereby impairing their performance as hydrogen getters. However, there is a need for a hydrogen getter material that is capable of gettering hydrogen in the temperature range of 150-300° C. This need is acutely felt in the oil well industry where downhole fiber optic systems are used. Hydrogen present in the downhole environment attacks the fiber optic reducing its transmission efficiency. This temperature range (150-300° C.) is well above the effective operating range of prior art unsaturated organic hydrogen getters but below that where metallic getters can be used.